Lipoprotein fraction analysis is useful for estimating the risk for coronary artery disease and for assessing the effectiveness of cholesterol lowering therapy. The objective of this study is to improve the analytical performance of current lipoprotein assays and to potentially develop new lipoprotein tests with improved diagnostic accuracy. In the past year, we have developed several alternative detergent solubilization procedures for adapting our previously developed sequential lipoprotein test to other lipoprotein homogenous assay tests that are in routine clinical use. The sequential lipoprotein test makes it possible to measure in a single reaction tube with an automated instrument all the major serum lipid and lipoprotein fractions (HDL-cholesterol, total cholesterol, triglyceride, and calculated LDL-cholesterol), thus significantly simplifying the laboratory procedure for lipoprotein fraction analysis. We also investigated the use of an immunoassay capture technique for the characterization of apolipoproteins, the major proteins on lipoprotein particles, by MALDI-TOF mass spectrometry. Using this technique, we were able to detect and characterize from serum the molecular forms for apolipoprotein A-I and apolipoprotein E, which are possible diagnostic markers. For example, some molecular forms of apolipoprotein E have been shown to be associated with the development of Alzheimer?s disease, but the currently used tests for identifying the different molecular phenotypes of apolipoprotein E are very labor intensive and expensive to perform. In the future, we plan to develop an assay for performing apolipoprotein E phenotyping by immunoassay capture followed by MALDI-TOF tandem mass spectrometry, which will allow the detection and differentiation of the various forms of apolipoprotein E by their molecular weight. We also plan to investigate several precipitation and filtration methods for developing a test that can be performed by routine clinical laboratories for measuring pre-beta HDL, a small size HDL particle that has recently been shown to be a better negative predictor for coronary artery disease than large size HDL particles.